Sound Emission

Technical basics

Sound propagates in gases, liquids and solids with the specific speed of sound (α).

Longitudinal wave

The particles move in the direction of propagation, this is called a longitudinal wave. Besides the speed of sound the frequency and the amplitude are the key characteristics of sound pressure variations. When a pump has mechanical vibrations (see also pulsation) the surface of this unit and the attached pipeline system act like a membrane of a speaker and shifts the air in vibration.

Loud noises in the frequency range between 1 kHz and 12,5 kHz is most disturbing for human ears. Often infrasonic is not taken into consideration. When exposing to infrasonic, humans feel bother, fantod, sickness or pressure on the chest.

Quieter than the quietest electrical motor on the market

Andrzej Szot One key to reduce noise is a streamlined pumping principle. Herold was the inventor of the rotary lobe pump with helical twisted rotors, the so called Wendelkolben®-Pump. The principle reduces the pulsation to the absolute possible minimum. Andrzej Szot, the technical director of the Polish sugar factory Ropczyce, was used to other pumps. After he installed Herold rotary lobe pumps he mentioned that the pump was so quiet, that he constantly had to look on the fan of the motor, to check if the pump is running.